feat(map): base layers - Topo, Light, Dark, Satellite, Esri Topo

Map tools > Layers > Map picks what the map is drawn from:
- Topo: OpenTopoMap, as before.
- Light and Dark: Esri's grey canvases, no labels, up to z16.
- Satellite: Esri World Imagery.
- Esri Topo.

Each layer has its own folder for downloaded areas (/sdcard/maps-light,
-dark, -sat, -esritopo; Topo stays in /sdcard/maps) and its own live-tile
cache. Live-cache records carry the layer.

Esri serves JPEG: decoded with LVGL's tjpgd (LV_USE_TJPGD), whatever the
file name says. The layer is kept in NVS (mc_ui/layer); switching waits
while a download or a deletion runs in the current folder.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/UITask.cpp

@@ -95,6 +95,7 @@ static bool s_chats_stale = false;   // Messages: a refresh waits for a held row
 #include "LvglPort.h"
 #include "lv_mem_psram.h"
 #include "HistoryStore.h"
+#include "map/MapLayers.h"
 #include "map/LiveCache.h"
 static histstore::SdArchive s_archive;   // message history on the SD card
 namespace storeview { static void stopWalk(); }   // StorageScreen.h
@@ -1429,7 +1430,7 @@ extern "C" EMSCRIPTEN_KEEPALIVE int sim_scroll(int dy) {
 #if defined(SIM_PLATFORM) && defined(__EMSCRIPTEN__)
 // The simulator page opens a screen by name (screenshots of the layout):
 // home, chats, contacts, settings, settings:<page>, nearby, map, navmap, places, clock, radio,
-// gps, diag, compass, storage, repeater, wifi, bot, quick, node, channel.
+// gps, diag, compass, storage, repeater, wifi, bot, quick, node, channel, layer:<n>.
 extern "C" EMSCRIPTEN_KEEPALIVE int sim_ui_show(const char* name) {
   if (!s_ui || !name) return 0;
   UITask& u = *s_ui;
@@ -1442,6 +1443,7 @@ extern "C" EMSCRIPTEN_KEEPALIVE int sim_ui_show(const char* name) {
   else if (!strcmp(name, "map")) u.openMap(false);
   else if (!strcmp(name, "navmap")) u.openMap(true);
   else if (!strcmp(name, "places")) { u.openMap(true); u.navTargetsPopup(); }
+  else if (!strncmp(name, "layer:", 6)) u.setMapLayer(atoi(name + 6));   // the map's base layer (MapLayers.h)
   else if (!strcmp(name, "clock")) u.showClock();
   else if (!strcmp(name, "radio")) u.showRadio();
   else if (!strcmp(name, "gps")) u.showGps(false);